The show revolves around two cats--White Kitty and Black Kitty--who are both owned by a nameless little girl. Black Kitty, the jealous [[TheUnfavorite unfavorite]], always tries to off White Kitty in a number of heinous and creative ways, but they all backfire violently.

Compare HappyTreeFriends, a similar series by the same studio.----!!Goodbye Kitty provides examples of:* AccidentalHero: Brown Puppy.* AccidentalMurder: Black Kitty tries to murder White Kitty in one episode by tricking him into walking off a cliff. Instead, three girls end up falling off the cliff. Ultimately subverted when they survive.* BlackComedyRape:** "Sun of a Bitch" ends with [[spoiler:Black Kitty getting anally raped by a lion]].** Implied at the end of "Kittycide".* BloodyHilarious[=/=]FamilyUnfriendlyViolence: As expected, as it's from the same studio as Happy Tree Friends.* ButtMonkey: Black Kitty, oh, so much.* {{Catchphrase}}[=/=]TitleDrop: "Goodbye, Kitty!".* CatsAreMean[=/=]CuteKitten: Black Kitty and White Kitty, respectively.* DisproportionateRetribution: The entire reason Black Kitty tries so hard to kill White Kitty is out of jealousy. Subverted as the retribution in question never happens.* [[spoiler:DrivenToSuicide]]: [[spoiler:How Black Kitty finally manages to kill White Kitty in the season finale, appropriately entitled "Kittycide": by giving the girl a bunny for her birthday, with which she replaces White Kitty, who commits {{Seppuku}}. However, White Kitty is subsequently [[BackFromTheDead brought back to life]] by Black Kitty's SwissArmyTears after realizing how much he actually misses him.]]* FailureIsTheOnlyOption* GangBangers: One episode has Black Kitty attempt to get White Kitty killed by gangsters. Naturally, they decide to [[CrowningMomentofFunny shoot Black Kitty instead]].* HoistByHisOwnPetard: A lot of Black Kitty's deaths are caused by this.* IdiotBall: At least once. In the episode "Dance of Death", Black Kitty attempts to gas White Kitty with the old exhaust-hosepiped-to-car trick, only to be beset with the hose repeatedly popping out of the exhaust pipe. [[spoiler:Rather than holding the pipe in, he chooses to ''inhale the exhaust'' to ferry it into the car itself. Unsurprisingly, he dies quite horribly indeed.]]* JerkAss: Black Kitty.** Also the girl, to an extent: she outwardly neglects Black Kitty in favor of White Kitty. [[spoiler:[[MediumAwareness In fact, she is actually aware of Black Kitty's constant failed attempts to kill White Kitty and resulting deaths]], and is blissfully indifferent to it. Black Kitty ultimately proves her shallow affections by giving her a bunny in the season finale, leading her to start neglecting White Kitty as well. At this point, both Kitties decide that she isn't worth the trouble they go through, so they...]]* [[spoiler:KickTheSonOfABitch]]: [[spoiler:White Kitty and Black Kitty arrange to have the girl kidnapped by the Pedobear after she starts neglecting them both.]]* [[LaserGuidedKarma Laser Guided]] KarmicDeath: Every time Black Kitty tries to kill White Kitty.* OnlyKnownByTheirNickname: While White Kitty and Black Kitty are referred to in the episode descriptions as Goodbye Kitty and Black Cat respectively, neither one one has a confirmed name, though fans tend to use the former names. The fact that White Kitty is called such as a rock star helps.* PreciousPuppy: The brown puppy that sometimes show up.* RuleOfThree: Black Kitty usually makes three attempts on White Kitty's life per episode, and dies (or is at least maimed) as a result each time.* TheyKilledKennyAgain: Black Kitty.* TheUnfavorite: Black Kitty.* VoodooDoll: One episode involves Black Kitty using this in an attempt to kill White Kitty. Unfortunately for him it ends up being turned into a Black Kitty voodoo doll when Brown Puppy covers it with black paint...subsquently he proceeds to rip it apart with his teeth causing Black Kitty a gruesome death.* WhamEpisode: The season finale. [[spoiler:Black Kitty finally kills White Kitty, but realizes his life is not complete without White Kitty and brings it back to life. The two then determine their owner to be the true cause of their problems, take their sweet revenge on her, and decide to continue their usual routine under a much happier pretext.]]----